Skeletal animation

Skeletal animation is a processor-efficient and relatively simple animation system that can simulate any jointed object, from people to insects to machinery.

The titular skeleton is a hierarchy of jointed but individually rigid bones that are manipulated in the same way as a real skeleton. Vertexes are 'enveloped' to the appropriate bone and move with it; the bone in turn moves with the bones above it (e.g. the hand follows the forearm). Polygons that cover joints between bones stretch and compress as the skeleton moves.